Process of reducing products of carbon monoxide



Patented Dec, 31, 1929 UNITEDSTATES PATENT orrlcr.

ALPHONS O. JAEGI JR, F GRAFTON, PENNSYLVANIA, ASSIGNOR TO THE SELDEN COM- PANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF DELAWARE PROCESS OF REDUCING PRODUCTS OF CARBON MONOXIDE [Ne Drawing. Original application filed September 9, 1925, Serial No. 55,392. Divided and this application filed November 8, 1927. Serial No. 232,003.

This invention relates to a process of pre paring reduction products of carbon monoxide. More particularly the invention relates to a catalytic reduction of carbon monoxide in presence of hydrogen or gases containing hydrogen in stages under optimum conditions for each stage.

Carbon monoxide is reduced in definite stages according to the following reactions I C0 H2=CH2O 0. 7 Cal) 11 01120 H2=CH3OH 27. 9 Cal). 111 CHSOH HQ=CH4 H2O 23. 9 Cal) stitutes one of the features of the present invention that the reactions for each of the three stages are caused to take place under the conditions of heat, pressure and chemical catalysts best suited to produce a maxlmum conversion in each stage.

The reactions are reductlon or hydrogenation reactions and the catalysts to be used belong to thegeneral class of reduction catalysts. tion catalysts .are not equally effective in the diiferent stages and that it is necessary to accurately proportion and tune the catalysts for each stage. Thus many reduction catalysts in-concentratlon suitable for good yields tend to carry the reactions too rapidly through the stages and result in the formation of large .amounts of methane and side reactions. I- have found therefore that is necessary for best results to damp the activity of the catalysts in stages I and II and this constitutes a further feature of my invent} on.

For the purpose of the present invention, reduction catalysts may be divided into two main classes namely, strong reduction catalysts such as iron, nicke l,cobalt and palla- I have found, however, that all reduc- I dium, and mild reduction catalysts such as copper manganese, cadmium, zinc, lead, tin, magnesium, silver, gold and platinum. The

elements may be-prcsent in the form of the metals, their oxides, hydroxides, salts, bothsimple and complex, and other compounds. In the case of zinc I have found that the best results are produced when part at least of the element is in the form of zinc dust and this constitutes one of the features of the inven tion. Single catalysts may be used or mixtures of difler'ent catalysts.

I have found that even the mild reduction catalysts referred to above tend to cause too violent reactions, particularly at higher tem-.

peratures, for example, temperatures in excess of 300 (1., and tend to produce sidereactions such as the formation of higher alcohols, ketones, higher aldehydes, acids and paraflines or mixturesof the above, and result in large yields of methane.

I have found thatthe activity of the mild reduction catalysts may be damped by mix.- .ing or combining these catalysts with catalysts having opposite functions, namely, oxidation catalysts. Among the oxidation catalysts I include those which are commonly used in. the vapor phase, catalytic oxidation of organic compounds, such as compounds of chromium, vanadium, manganese, tltanium, mo-

' lybdenum, tungsten, cerium, thorium, uranium, zirconium and the like. These catalysts may be in the form of their oxides,salts,both simple and complex, and other compounds.

Single oxidation catalysts may be used as diluents to damp the activity of the reduction catalysts or mixtures of different oxidation catalysts may be so used. The catalysts may be used as such or may be coated on or absorbed incarriers such as pumice, asbestos,

kieselguhr, silica, porcelain, calcined magnesia, soapstone, roughened quartz, silicates and similar minerals.

The reduction and oxidation catalysts may be separately 1 formed and the fragments mixed or arranged in layers or a particular mixture of best efiiciency can be achieved by impregnating-solutions of reduction and oxidation catalysts into porous carriers.

The strong reduction catalysts, iron, nickel,

cobalt and palladium should be avoided or used in great dilutions. I have found that for certain purposes-concentrations not exceeding 3% of the strong reduction catalysts may be used. It is, not sufficient to avoid the presence of strong reduction catalysts in stages I and II at the beginning of the reac- This may be advantageously carried out by means of a water spray or by passing the gases through an absorption tower after passing through the converter in which the reaction of stage I is carried out.

Owing to the fact that the reactions are equilibrium reactions, a high gas speed is desirable and should preferably be sufficiently high so that the volume of gas in the converter or converters is changed more than thirty times an hour.

The reduction can be carried out in separate convertersfor each stage using the temperature and pressure best suited for that particular stage and if necessary, supplying additional gas between stages. Thus stage I may be carried out in one converter, the gases compressed and forced into another converter mixed with additional hydrogen or hydrogen containing gases where necessary, reduced further in the second converter according to the reaction of stage II and finally reduced in a third converter with or without the addition perature's and there is an increased tendency to form side reactions. 450 C. therefore represents the upper limit for eflicient operation and 200 C. is, roughly the lower limit, as the reaction proceeds too slowly at lower temperatures to be economically used. Pressure aids the reaction but the pressure used should be determined in' combination with the activity of the catalysts and the temperature, as higher pressures not only tend to accelerate the reaction of stage I but they also'tend to cause side reactions particularly condensation reactions of formaldehyde.

'The proportions of carbon monoxide and hydrogen may be that of equal volumes but.I have found that an excess of hydrogen is desirable as it not only pushes the equilibrium toward the production of formaldehyde in accordance with the mass action law but, due to the peculiar character of the catalysts used, the excess hydrogen does not exert any deleterious effects.

The catalysts used consist of a mixtureof mild reduction catalysts and oxidationcata- 'a converter consisting of a nickel alloy is used it should preferably be provided with a lining which is inert or a mild reduction I catalyst, for example, copper linings maybe 135 advantageously used in many cases.

Formaldehyde may be recovered by sudden cooling, preferably by means ofa water spray.

Where the formaldehyde is not to berecov- 'ered the gases with or without addition of no hydrogen may be directly introduced into a two ormore stages in a single converter arranging the different catalysts in zones or mixed together or alternating zones of the various stages. The alternation of catalytic zones tuned to the different stages is of advantage particularly where stage I and stage II are combined since the reaction of stage II removes formaldehyde formed in stage I and thus -upsets the equilibrium so that the further formaldehyde is rapidly formed by bringing the remaining gases into contact with more of the catalyst which is partlcular- 1y suited for the reaction of stage I. I

" Stage I represents a slightly endothermic reaetion'and takes place with reduction involume. I have found that at temperatures above 450 C. efliciency falls as the formaldehyde formed rapidly decomposes at such temsecond converter after cooling and there" further reduced to methyl alcohol or methane.

The transformation of formaldehyde into methyl alcohol, according to the reaction of stage II, is a strongly exothermic reaction and accordingly exccessive temperatures action is carried out in a separate converter,

the gases from the first stage, with or without separation of some of the formaldehyde formed, are pumped after cooling into a converter at high pressure and any added hydrogen or hydrogen containing gases which may be necessary may be directly pumped into the converter. In general, the pressures used 130' in stage II are much higher-than those in stage I but a wide variation is possible.

1 have found that a very advantageous method of carrying out stages I and II in separate converters consists in connecting these converters to separate stages of a multistage compressor. The converter in which stage I is carried out is connected to the low pressure stage of the compressor and the gases from the first converter are fed into a higher pressure stage of the compressor together with any additional hydrogen which may be necessary and pumped into the second conways described in connection with the catalysts for stage I. Strong reduction catalysts should be avoided, both in the original catalyst charge'ofthe converter andthe material of the converter walls. Care should also be taken to prevent the introductionof strong reduction catalysts in any form in the gas stream, as has been described inconnection with stage I. The presence of'strong reduction catalysts in extremely high dilutions may be tolerated but they should not be in excess of 3% of the total catalyst weight.

The methanol produced in stage II may advantageously be recovered from the exhaust gases by cooling followed by absorption in activated charcoal, silica-gel, or similar absorbents. Solvents of methanol may also be used. The reaction is preferably carried' out in a rapidly moving gas stream which should have about the same velocity as in stage I, namely, suflicient to change the gas volume in the converter more than thirty times per hour.

Stages I and II may advantageously be combined in' a single converter and thismethod presents many advantages. Formaldehyde is a relatively unstable compound whereas methyl alcohol is comparatively stable and by carrying out the reaction in a single converter, particularly where alternate layers or zones of formaldehyde and methyl alcohol catalyst are used, the formaldehyde formed is at once reduced to methyl alcohol and this permits the production of further amounts of formaldehyde in the next succeeding formaldehyde catalysts zone, owing to the fact that the equilibrium is upset by the removal of formaldehyde. A similar effect is produced by mixing the two catalysts together.v When the reaction is carried out in a single converter formaldehyde of course cannot be recovered and the main product is methanol.

found that the use of zones of catalysts of tributed over all of the catalyst.

in the direction of gas flow and different .to prevent local over-heating of portions of the catalyst with a resulting decomposition, formation of side reactions and over-reduction. High gasvelocities which have been referred to above are one of the means which I have found to be advantageous in preventing the local over-heating and'I have also increasing activlty in the direction of the gas stream are very effective in preventing local over-heating since 'the most active catalysts contact with the most nearly spentgases and the evolution of heat is evenly dis- Theend-othermic stage 1 is further aided by the exothermic. stage II. The increasing activity of catalysts in the direction of the gas flow may be brought about invarious ways. a The concentration of the catalysts may be varied. Proportions of reduction and oxidation catalysts may be varied to bring about an increasing percentage of reduction catalysts catalysts of increasing specific catalytic activity, may be used, for example, relatively weak surface effect catalysts such as activated carbon, coke and similar porous materials may be present with the first layer followed by layers containing elements and I compounds of tin, silver, gold, lead, copper, cadmium, zinc, in the order named which represents av series of increasing activity. The

oxidation catalysts may also bepresent in a series of decreasing activity in the direction of the gas flow and I have found that such a series for the methanol stage consists in thorium, cerium, zirconium, vanadium, titanium, molybdenum, uranium, manganese and chromium. Various combinations of these methods may also be used but the net effect should always be an increasing reduc' tion catalyst activity in the direction of the gas flow and care should be taken. not to use reduction catalysts in excess in any layer used in stage I. p V

The gases coming from the methyl alcohol converter with or without recovery of methyl alcohol can be further reduced to methane in a separate converter, with or without pressure, at temperatures above 150 (3. The strong reduction catalysts, iron, nickel, cobalt and palladium should beused in large quantities singly or in combination and should be v can be partly or wholly in the form of their and the catalysts become inoperative. 600 C.

oxides, easily decomposed compounds, salts (simple and complex) or othercompounds singly or in combination. The proportions of reduction and dehydrating catalysts may be varied but I have found that it is advantageous to use the reduction catalysts in excess.

Stage III is strongly exothermic and tends to proceed violently. A very rapid gas flow must be used when operating under pressure and preferably the converter should be cooled. I have found that a gas .speedsuflicient to change the gas volume in the converter at least thirty times or more an hour is desirable. If the above mentioned precautions are not taken the reaction may become uncontrollable is the upper limit and from 200 C. up commercially practical reaction velocities are rendered possible. The gases before entering the methane converter may advantageously be so changed in composition by the addition of hydrogen or gases rich in hydrogen that the final gas after passing through the converter is pure methane.

The reduction of carbon monoxide to methane in stages as described above presents the advantage that the evolution of heat in the stages II and III is divided over the three stages and the danger of over-heating the catalysts in the converter due to the very violent reaction is lessened. Thus comparatively large amounts of gas can be caused to react in a definite time and high pressure can be used without involving great difficulties from a heat engineering stand-point.

The methane process can also be combined with the formaldehyde and methyl alcohol steps above described in a single converter by arranging the methane catalysts in zones-or miin'ng with the formaldehyde and methyl alcohol catalysts. The activity of the catalysts may advantageously be increased in the direction of the gas flow as described above in connection with the production of the formaldehyde and methyl alcohol and the samemethods or combinations can be used. The methane catalysts form a series of increasing catalytic activity as follows: iron, cobalt, nickel and palladium. A similar increase inactivlty in the direction of the gas flow can be carried out with the dehydrating catalysts by,

using this in the following series of increasing activity: zinc oxide, vanadium trioxide, ferric oxide,'molybdenum pentoxide, uran ium oxide, zirconium dioxide, beryllium oxide, titanium dioxide, silicon dioxide,

chromous oxide, aluminum oxide, thorium oxide. A variation of activity, by varying the concentration may also be used either alone or combined with the use of different dehydrating catalysts of increasing activity in a manner similar to that described in connection with the reduction catalysts. Methane catalysts may also be used with inert cementing mixtures such as albumen, sugar,

dextrine or catalytically active cementing multi-stage compressor. Circulating pumps may, of course, also be used'in connection with any single stage. 7

Other gases such as nitrogen, carbon dioxide, methane, rare gases of the air, and small amounts of oxygen are not harmful. The gases should, however, be free from contact poisons such as sulphur, arsenic, hydrogen phosphide and metal compounds which exert a deleterious action on the reduction catalysts.

The efficiency of the catalysts in all of the stages can be greatly enhanced by using catalyst carriers of great surface energy.

I have found that finely'divided materials such as kieselguhr, colloidal silicic acid. as-

besto's flour, pumice flour, quartz flour or finely ground silicates having an average particle size of 20 microns or less when used as.a carrier for the reduction and oxidation catalysts or reduction and dehydration catalysts greatly enhances their efficiency. In some cases the increase in efficiency amounts to 20% or more and finely divided carriers activators of the catalysts. I am not certain as to why the finely divided carriers exert this remarkable effect which appears to be much greater than that due to the mere increase in surface. I am of the opinion, however, that the colloidal character of the carriers, that-is to say, the enormous surface compared to .thevolume of the voids between' may or may not subsequently prove to be.

true. particularly effective method of impregnatlng finely divided carriers as described above, consists in the use of solutions of complex salts or compounds of the cata lysts which are thus very evenly and finely distributed on the particles and on'calcination leavethe catalyst in an evenly distributed form having an immense surface.

of this type may be considered as positive I The impregnatedfinely divided carriers are preferably formed into granules by pressing with or without a cementing material such as organic adhesives, sugar, dextrine and. the like, or salts of zinc, lead or magnesium and potassium or sodium silicate. The granules are dried and calcined and if ex cess alkali is present it may advantageously be washed out. It should be understood, of course, that the finely divided material may be used as part or all of the carrier and may be associated with more massive carrier fragments as a coating. vIt is also unnecessary to use exclusively solutions of complex catalyst compounds or salts as impregnated media. While such solutions are preferable in most cases, other methods of impregnating the catalysts may be employed'either singly or in combination with impregnation by means of solutions of complex catalytic compounds.

The invention will be described more fully in the following specific example but it should be noted that the invention is not limited to the details therein set forth.

Example '1 A converter is charged with a catalyst formed by mixing 100 parts of ammonium vanadate, 100 parts of manganese carbonate and 25 parts of chromic acid with 500 parts of calcined kieselguhr. The mixture is preferably in the presence of sufficient moisture to form a soft dough or paste and this is treated with a solution of 25 parts of ammoair and then reduced with hydrogen at about I A purified water gas which is preferably prepared by the gasification of wood charcoal, and which contains about 48% hydro gen, 45.5% carbon monoxide, 4% nitrogen, 1% carbon dioxide and 1.5% methane is introduced itno the low pressure stage of a compressor and compressed to about 5 to 10 atmospheres and heated to about 20030'0 C.

' whereupon it is passed over the catalyst in a very rapidv stream;

Formaldehyde can be recovered in a good yield by a sufficiently rapid cooling of the gas stream, particularly by means of a water spray. Instead of removing formaldehyde the gases coming from'the converter may be cooled and additional hydrogen added to bring the concentration of hydrogen to I or more and the gases then compressed in a high pressure stage of a compressor to about 200 atmospheres or higher and passed through steel.

a high pressure cylinder which may be advantageously lined with bronze.

, The hi h pressure converter can be heated electrically either from the outside or from the inside, depending on the quality of the When interior heating is used, the elements of the strong reduction catalysts are to be avoided in the resistance material, as otherwise carbon is precipitated. Preferably a current of low voltage and high amperage is used in order to simplify the problem of insulation. The heatingmay also be carried out by means of a high pressure coil or helix which is lined with copper on the outside and is built into the converter. Water under pressure or mercury or other suitable liquids may be used and are heated to the necessary temperature and pumped through the coil.

.The coil serves also to remove heat of reaction heating.

The catalyst is prepared as follows:

The first layer of catalyst consits in a mixture of 200 parts of kieselguhr, 20 parts of short fibre asbestos and 5 parts of dextrine to which is added an ammoniaoal silver nitrate solution equivalent to 88 parts of silver oxide and illl-il-IDIIIOIllUIIl vanadate solution.

dust, which are mixed in a moist state and pressed into granules. The next layer is prepared by coating 264 parts of cadmium oxide with 180 parts of chromic acid in solution and treating with ammonium vanadate containing 5 parts of vanadic acid. After evaporating the excess water the mixture is pressed into granules, using starch as a bindor if necessary. A layer of 138' parts of zinc dust, 52 parts of zinc oxide and 55 parts of chromium oxide follows; The catalyst is. formed by mixing the moistened pasty mass,

drying and pressing. Then follows .a double layer of 84 parts zinc oxide, 64: parts zinc dust and 100 parts of chomic acid mixed with 200 parts of kieselguhr formed and dried.

- The highly compressed gases from the formaldehyde converter are passed over the above described catalyst in the high pressure converter at about 300 to 400 C. at a high rate of speed. Preferabl the gas speed should be high enough so t at the volume of gas in the converter is changed more than thirty times per hour. The exhaust gases on cooling under pressure give excellent yields of methyl alcohol. The gaseous methyl alcohol remaining in the exhaust afterv cooling may be absorbed in activated carbon or slim ilar absorbent.

The remaining gas can be returned to the and 15 parts of aluminum'oxide applied in- 400 C. Theproduct is mainly methane.

first converter after adjusting its compositionor it may be partially or wholly passed into a third converter with or without methyl alcohol. A considerable amount of additional hydrogen should be added and the gases should pass over a contact mass consisting in a layer of 100 parts of bauxite and 110 parts of reduced iron cemented with water glass, then through a layer consisting in a mixture of 120 parts of nickel carbonate and 10 parts of aluminum oxide impregnated into 100 parts of pumice fragments followed by a layer of 100 parts of thorium oxide fragments impregnated with 3 parts of palladium and 10 parts of nickel nitrate. layer of'150 parts of kieselguhr or colloidal silica impregnated with 30 parts of nickel applied. in the. form .of nickel ammonium nitrate the form of sodium aluminate. The pressure may advantageously be from 2 to ,5 atmospheres and the temperature from 250 to Example 2' A high pressure converter which maybe advantageously formed by a plurality of steel tubes shrunk onto each other is provided with an inner lining or aluminum and contains the following catalyst layers:

1. 200 parts of kieselguhr and 18 parts of silver vanadate thoroughly mixed'with- 100 parts manganese dioxideand 6 parts of dextrine and formed intofragments.

' 2. 100 parts of thorium oxide coated with .9 parts of copper and 10 parts of zinc produced by evaporating complex ammonium salts of copper and zinc nitrate on the thorium oxide fragments.

3. Contact layers as described for the methyl alcohol converter in Example 1.

' A gas mixture of 20%-35% carbon monoxide and 65%85% hydrogen and containing less than oxygen is passed through the converter at a temperature of 200450 C. and

methane in afurther converter as described in Example 1 or the methyl alcohol may be recovered.. In the latter case, the remaining gases ma advantageously be recirculated with suita leadditions of fresh gas.-

Instead of the layers of methylalcohol catalysts described in Example 1,t he follow-- 'ing contact layer can'be efliciently used as the third layer in the converter. 130 parts of cadmium oxide, 220 arts of leadoxide,

200 parts of chromic acid and potassium silicate in-amounts less than those correspondingto 100 parts KOH are mixed thoroughly A- further with, 300 partsof'kieselguhr dried at 200 C. in carbon dioxide current. The dried mass can be freed from alkali by washing with water and may'then be dried again and broken into fragments. A further excellent contact layer is formed by a mixture of 130 parts cadmium oxide, 10 parts zinc dust, 200

A high pressure converter, provided with an aluminum lining in the inner tube, is charged with the catalyst mentioned in Example 2 and further with a deep'layer of catalyst as described in connection with the methane. converter in Example 1, and a mixture of 25 volumes of carbon monoxide and volumes r of hydrogen is passed through=at a pressure of- 20 atmospheres and 300 0., the gas speed being exceedingly high. The excess reaction heat can be effectively removed by a cooling coil through which water islpumped at high pressure, a good yield of methane resulting.

' It will be seen that the present invention provides a novel and improved method of reduclng carbon monoxide operating ona different chemical principle than has been hith-fl erto employed. invention also. includes improvements in each of the three stages of reduction and these improved stage reactions, as well as the combination ofstages, are included in my invention.

A further important advantage feature of the present invention consists in rious' stages associated with or impregand I 'the highly effective catalysts used in the vanated on finely divided materizfl havin an average particle size of 20 microns or ess. The lmpregnatlon of these finely dlvlded carriers wholly or in partby solutions of complexcompounds or salts of the catalytic elements constitutes a further advantage and feature and produces a catalytic layer on the carrier particles which is of great uniformity and homogeneity-and is exceedingly eflective in the reaction.

On the contrary, in the present application 7 mild re- This application is division ofmy copending application, Serial No. 135,393, filed.

carriers of relatively insignificant catalytic activity and the reaction stage from methyl alcohol to methane taking place in the presence of strong reduction catalysts.

2. A process of reducing carbon monoxide or carbon monoxide containing gases, which comprises causing the gas to react with hydrogen-containing gases in successive stages to form formaldehyde, methyl alcohol, and then methane without isolating intermediate products formed, at least one of the first two stages taking place-in the presence of mild reduction catalysts associated with oxidation catalysts, both being incorporated in porous carriers ofrelativel insignificant catalytic activity, each stage being carried out under reaction conditions for high efliciency in the reaction carried out in the stage and the reaction stage from methyl alcohol to methane taking place in the presence of strong reduction catalysts.

3. A process of reducing carbon monoxide or carbon monoxide containing gases, which comprises causing the gas to react with hydrogen containing gases in successive stages to form first formaldehyde, methyl alcohol and then methane without isolating intermediate products formed, atleast one of the first two stages taking place in the presence of. mild reduction catalysts associated with oxidation catalysts, both being incorporated in porous carriers of relatively insignificant catalytic activity, each stage being carried out in the presence of catalysts and under reaction conditions favorable to the reaction carried out in the stage.

4. A process of reducing carbon monoxide,

and carbon monoxide containing I gases, which comprises causing the gas to react with hydrogen containing gases in successive states to form fo'rmaldehyde, methyl alcohol and then methane without isolating intermediate products formed, 'both of thefirst two stages being carried out in the presence of mixtures of mild reduction catalysts and oxidation catalysts, at least one such mixed catalysts being-associated with porous carriers and the reaction stage from methyl alcohol to-methane taking place in the presence of strong reduction catalysts.

5. A process of reducing carbon monoxide and and carbon monoxide containing gases, which comprises causing the gas to react with hydrogen containing gases in successive stages to forlnformaldehyde, methyl alcohol and then methane without isolatin intermediate products formed, both of the first stages being carried out in the presence of mixtures of 'mild reduction catalysts and oxidation catalysts, both such mixed catalysts being associated with porous carriers andthe reaction stage from methyl alcohol to methane taking place in the presence of strong reduction catalysts.

(i. A process of reducing carbon monoxide carbon monoxide containing gases, which compr ses causing the gas to react withhydrogen containing gases in successive stages to form formaldehyde, methyl alcohol, and then methane without isolating intermediate products formed, the first stage being carried out in the presence of a mixture of mild reduction catalysts with an excess of oxidation catalysts, the second stage being carried out in'the presence of an excess of mild reduction catalysts mixed with oxidation catalysts, the catalysts in at least one of these stages being associated with porous carriers and the reaction stage fromcmethyl a1 cohol to methane taking place in the presence of strong reduction'catalysts.

7. A process according to claim 1, in which at-least two successive stages are carried out in the same converter which is provided with zones of catalysts corresponding to the-different reaction stages.

8. A method according to claim 1, in which reaction gases, the converters, and catalysts used in carrying out the first two stages are substantially free from strong reduction catalysts.

9. A process according to claim 1, in which the oxidation catalysts are in excess over the mild reduction catalysts in the first stage.

10. A method of producing methyl alcohol which comprises causing gases containing formaldehyde and hydrogen to react in the presence of a mixture of mild reduction catalysts and oxidation catalysts associated with p'orous'carriers of insignificant porous activity, the mild reductioncatalysts being in excess.

11: A method according toclaim 10, in which the gases, catalysts, and converter structure are substantially free from strong reduction catalysts.

12. A method of preparing methyl-alcohol,

cant catalytic activity, the reduction catalysts being in excess.

' 13. A method of producing methyl alcohol which comprises causing carbon monoxide to react with hydrogen containing gases in the presence of mild reduction catalysts associated with an excess ofoxidation catalysts under conditions favorable to the formation of formaldehyde, and causing the formaldehyde so produced, without separation'from the gas stream, to react with hydrogen in the presence of mild reduction catalysts and oxidation catalysts associated with carriers ofinsignificant catalytic activlty, the mild reduction catalysts being in excess.

14. A method according to claim 13, in

which the reaction gases, the catalysts, and

. converter structure are substantially free from strong reduction catalysts.

converter and the catalysts are arranged in 1 alternate zones or layers. 1

- 16. A method of producing methane, whichcomprises causing gases containing formal dehyde to react with hydrogen containing gases in the presence of mild reduction catalysts andoxidation catalysts associated with porous carriers oif insignificant catalytic activity, the mild reduction catalysts being in excess, and causing the methyl alcohol thus I produced, without separation from the gas stream, to react with hydrogen in'the pres.

ence of'strong reduction catalysts.

17. A method of producing methane, which comprises causing gases containing carbon monoxide to react with hydrogen containing ases in the presence of mild reduction cata ysts associated with an'excess of oxidation. catalysts, causing the formaldehyde thus produced, without separation from the gas stream, to react with mild reduction catalysts and oxidation catalysts, the mild reduction catalysts being in excess, andcausing the methyl alcohol thus produced, without separation from the gas stream, to react with strong reduction catalysts, the catalysts vin at least'one of the first two stages being associated with porous carriers of insignificant catalytic activity.

Signed at Pittsburgh, Pa.,'this 5th day of November, 1927. ALPHONS O. JAEGER.

orous' 15. A method according to claim 13,. in. 'which both stages are carried out in the same 

